The invention relates to a motor vehicle having a front engine and all-wheel drive of the type wherein the wheels of the front axle are driven continuously, while the drive for the wheels of the rear axle is capable of being connected directly by way of a lockable center differential or automatically by means of a viscous coupling device arranged in the driveshaft line between the front axle and rear axle. Thus, the front and rear axles are essentially rigidly coupled together with regard to torque, and in the train of the driveshaft line transmitting the torque between the front and rear wheels there is provided at least one free-wheeling device with a free-wheel lock, preferably a grip roller free-wheeling device. The free-wheeling device is arranged and designed so that--in the unlocked state--its free-wheel part coupled with the rear-axle drive is capable, during forward driving, of overriding its free-wheel part coupled with the front-axle drive.
A motor vehicle of this type is disclosed in, for example, DE-OS No. 33 17 247. In this known vehicle, at least one free-wheeling device with a free-wheel lock, for example a grip roller free-wheeling means, is arranged in the train of the driveshaft line to transmit the torque between front and rear wheels. The free-wheeling device is designed so that a reduction of the rotational speed of the front wheels owing, for example, to actuation of the service brake, cannot be transmitted through the driveshaft line to the rear wheels. This ensures that the road stability of the vehicle is not impaired, even in the case of overbraking of the front wheels, due to the free-wheeling device which prevents a locking of the front wheels from having an effect on the rear wheels.
To make an all-wheel drive possible even in reverse, the free-wheeling device is equipped with a free-wheel lock which may be locked either manually or alternatively automatically, for example, upon shifting into reverse.